BIOLOGICALLY ACTIVE NATURAL PRODUCTS: AGROCHEMICALS - CHAPTER 13 doc

13
Tobacco as a Biochemical Resource: Past,
Present, and Future
David A. Danehower, R. C. Long, C. P. Wilcox, A. K. Weissinger,
T. A. Bartholomew, and H. E. Swaisgood
CONTENTS
13.1 Introduction
13.2 Bioprocessing of Tobacco — The Past
13.3 Tobacco Processing — The Present
13.4 Other Product Streams from Bioprocessed Tobacco
13.4.1 Carotenoids
13.4.2 Terpenoids
13.4.3 Sugar Esters
13.4.4 Hydrocarbons and Waxes
13.4.5 Coenzyme-Q
13.4.6 Structural Carbohydrate
13.5 Tobacco Bioprocessing — The Future
References
ABSTRACT For over 50 years, researchers have been examining the potential to use
tobacco (Nicotiana tabacum, L.) for the production of numerous biochemical products. As
part of this effort, research at North Carolina State University has been conducted on the
selection of cultivars for optimal biomass and protein content, the genetic engineering of
tobacco to produce foreign proteins, agronomic production methods for bioprocessed
tobacco, upstream processing, and downstream purification procedures required to yield
such products. This chapter will present an overview of the progress that has been made in
tobacco bioprocessing since its inception. Studies conducted at NCSU will be used to illus-
trate the possibilities and pitfalls of bioprocessing tobacco. Based upon these studies, the
feasibility of using field grown tobacco as a “bioreactor” for production of fine biochemi-
cals will be discussed.
13.1 Introduction
When Columbus first arrived on the shores of North America, he found Native Americans

growing and using a plant unknown to Europeans. This plant held great spiritual significance
© 1999 by CRC Press LLC
to Native Americans. Scientists who followed in the footsteps of the early North American
explorers would later name this plant tobacco. Tobacco (Nicotiana tabacum, L.) farming
began in the early 1600s near the Jamestown colony in Virginia. As the use of tobacco prod-
ucts for smoking, chewing, and snuff was promoted in Europe, tobacco became a leading
item of commerce between the colonies and England. Notably, George Washington and
Thomas Jefferson both farmed tobacco. Thus, the history of America is inextricably linked
with the history of tobacco production.
Today, the production of tobacco in the Southeastern U.S. continues to be an important
contributor to the economy of that region. Tobacco income has allowed many small family
farms to remain self-sufficient. In North Carolina, tobacco accounts for over one billion dol-
lars/year in cash receipts at the farm gate.
43
At a profit of roughly $1000 to $2000/acre,
tobacco is the most profitable row crop grown in the U.S. In contrast, a good farmer can
expect a profit of $60, $100, or $200/acre for soybeans, corn, or cotton, respectively.
Despite its economic significance, the tobacco industry is in turmoil. The proposed legal
settlement between the states Attorneys General and the tobacco industry,
1
the widespread
recognition of the health hazards of tobacco and tobacco smoke, and a decline in tobacco
consumption have led farmers to question the future of the crop. These farmers are seeking
alternatives that might take the place of tobacco. Unfortunately, no other crop is likely to
be able to provide the level of income on an acre-for-acre basis. Truck crops such as toma-
toes, strawberries, and peaches yield profits similar to those of tobacco. Nevertheless, the
potential acreage in North Carolina from these crops is at least an order of magnitude less
than that of the current tobacco acreage. Substantial increases in the acreage of any of these
truck crops would lead to market saturation and a collapse of prices. If North Carolina
farmers are to diversify, what is required is the identification of a panoply of alternative

crops. Perhaps surprisingly, a growing number of researchers believe that one such crop is
tobacco grown for nontraditional use as a renewable biochemical resource.
This chapter describes past and current research on biochemical products from biopro-
cessed tobacco. These efforts date back at least to the early 1940s. Where possible, research
conducted at NCSU will be used to illustrate the problems and potential for tobacco as an
industrial crop. We also will discuss the biological and technological hurdles that must be
overcome to make such an industry possible.
13.2 Bioprocessing of Tobacco — The Past
Over 50 years ago, researchers at the USDA Eastern Regional Laboratory began to explore
the use of tobacco for the production of biochemical commodities. The regional labs were
established to study alternative uses for excess farm commodities. Among the products
examined for their commercial potential were nicotine, nicotinic acid, beta-carotene, cellu-
lose, waxes, chlorophyll, and citrate.
10,21,36,37
This research resulted in the development of a
commercial nicotine recovery process, an effort that was later abandoned as nicotine sul-
fate was supplanted by the first generation of synthetic insecticides.
Interest in extended uses of tobacco arose once again in the early 1970s when Kawashima
and Wildman
25,26
demonstrated that it was possible to isolate Ribulose bis phosphate Car-
boxylase-Oxygenase (RuBisCO, “Fraction 1 Protein”, or F-1-p) from tobacco using rela-
tively simple process technology.
61,62
RuBisCO catalyzes the reaction of atmospheric CO
2
with ribulose bisphosphate, a key step in the Calvin cycle. Because RuBisCO is found in
© 1999 by CRC Press LLC
abundance in all photosynthetic organisms, it holds the distinction of being the single most
abundant protein in the world.

Considerable work on the isolation of crude soluble leaf protein from green plants pre-
ceded the work by Wildman on tobacco. These “leaf protein concentrates” are used in both
animal and human diets.
44,47,52,54
Significantly, however, tobacco and a few closely related
species have been shown to be unique in their ability to produce a tasteless and odorless
high-grade crystalline Fraction 1 protein.
61,62
Because it can be isolated in high purity, has
high nutritive value,
17,29
and unique physiochemical properties,
4,49-51,57
tobacco-derived
RuBisCO has potential as a new protein for utilization in the food, medical, and cosmetics
industries. F-1-p has exceptional nutritional and functional properties including an excel-
lent amino acid balance, neutral taste and odor, hydrophilicity, jelling properties, texture,
and structural stability.
27
These properties compare favorably with those of casein, i.e., milk
protein. A driving factor for use of plant proteins is an increasing preference by consumers
for such proteins in place of animal-based sources. RuBisCO protein is in demand by the
food industry as a means of modifying existing products or fabricating new products with
improved quality and nutritional value.
High-grade proteins such as casein and F-1-p also are important for non-food uses
including there use as emulsifiers for personal care products.
55
While casein has been a tra-
ditional source of such proteins, increased demand coupled with tight supplies have led to
demand in the marketplace for casein substitutes. In addition, high purity, easily digested

proteins also are of interest in medicine. Patients with severe impairment of renal function
must restrict their intake of sodium and potassium.
17
Crystalline F-1-p is low in these ions
and could serve as a source of protein for such patients. In addition, F-1-p could also be
incorporated into low-residue, nutritionally complete diets for patients suffering from a
range of gastrointestinal diseases.
Wildman recognized the potential for F-1-p and began development of a process for the
large-scale isolation of Fraction 1 and residual plant proteins (Fraction 2 proteins, F-2-p)
from tobacco. Leaf Protein International was formed by Wildman and associates to further
this effort and a pilot plant was built near Wilson, NC. Working with Ray Long and
coworkers at NCSU, considerable progress was made towards the goal of developing agro-
nomic methods for the production of tobacco biomass and for producing crystalline Frac-
tion 1 protein using the pilot scale facility.
This work resulted in a prototype system for the agronomic production of green tobacco
biomass and subsequent recovery of F-1 and F-2 proteins. Agronomically, the system con-
sists of growing tobacco in fumigated beds at high plant densities. The plants are then har-
vested up to four times during the growing season. During the development of these
procedures a number of variables including plant variety, planting density, harvest sched-
ule, fertility regime, and pest control methods were examined.
5,34
The system consists of
direct seeding of tobacco into raised beds to produce a total seasonal yield of 180,000 lb/acre
of fresh biomass. This is approximately equivalent to 18,000 lb/acre of dry biomass of
which approximately 1800 lb is plant protein. Fertilization consists of an initial application
of 12-6-6 N/P/K at a rate of 75 lb/100 linear feet of bed, followed by re-fertilization of the
beds with 100 lb/100 linear feet of 15-0-14 after each harvest. Insect, weed, and disease con-
trol are accomplished using standard cultural practices used in traditional tobacco produc-
tion. A significant problem that has been encountered in this system is the development of
hollow stalk rot [Erwinia carotovora (Jones) Holland], following each harvest. Additional

work is needed to examine control methods for this organism. The green tobacco biomass
is harvested when the tobacco has reached a height of approximately 60 cm. A forage har-
vester is used to collect the plant material which is placed into wooden crates for transport
© 1999 by CRC Press LLC
to the processing facility. During this phase, it is important that the tobacco lamina main-
tain its turgidity. This is facilitated by close coupling of harvesting and processing. Prior to
processing, the tobacco can be cooled by percolating water through the tobacco biomass.
Tobacco bioprocessing (Figure 13.1) is initiated by chopping the green biomass followed
by immediate homogenization using a tissue disintegrator. Aqueous sodium meta-bisulfite
is added as a reductant prior to tissue disruption. The resulting green pulp is then passed
through a screw press, separating the solid biomass residue from the green juice that con-
tains plant proteins, starch, pigments, and other materials. Complete extraction and maxi-
mum recovery of protein requires re-extraction of the biomass residue. The resulting green
juice from this secondary recovery process is then added to the initial liquid stream.
The green extract is then passed through a heat exchanger and brought to a temperature
of approximately 48°C for several minutes.
61,62
This step coagulates the green, lipophilic
material in this fraction and is a key step in successful protein isolation. The resulting mix-
ture is centrifuged and the coagulated green “sludge” and starch are separated from the
aqueous stream. This stream exits the centrifuge as a clear amber liquid, similar in appear-
ance (but not taste!) to a dark ale. If necessary, further polishing of this fraction can be
achieved through an additional step such as bed filtration.
The dark amber liquid is transferred to a holding tank chilled to 5 to 10°C. If necessary,
the pH of the solution is adjusted to 5.5. The crystalline F-1-protein slowly precipitates and
settles over approximately 24 h at which time the protein is collected using an industrial
decanter. The aqueous F-2-p stream resulting from this step is typically pale amber — sim-
ilar in appearance to a good Pilsner beer. This F-2-p fraction contains native plant enzymes
as well as salts, soluble carbohydrates, and other water solubles. The F-1-protein concen-
trate can be re-solubilized by adjusting to pH 8.0. Repeated solubilization and precipitation

can be used to polish this fraction and remove residual foreign materials. F-1-p is obtained
in solid form by filtration of the acidic mixture or spray-drying of the basic solution.
Fraction-2-proteins are recovered by adjusting the pH of the pale amber solution to 4.5
followed by cooling to 5-10°C for 24 h. As in the case of F-1-p, this leads to precipitation of
F-2-p. Recovery of the precipitated protein mixture is identical to that described for F-1-p.
The “Fraction 2” proteins which consist of a mixture of the residual plant proteins
(enzymes) after RuBisCO recovery also are of commercial significance. F-2-p leaf proteins
(and total leaf protein concentrates) can be used commercially as animal feed supplements.
45
Among the naturally occurring tobacco constituents found in F-2-p are protease inhibi-
tors. These macromolecules are especially prevalent in chlorotic tobacco leaf tissues.
30
In planta, protease inhibitors are believed to function as a mechanism of defense against
herbivores.
20
Significantly, protease inhibitors are of interest in the medical community as
anticarcinogens and radioprotectants.
56
A collaborative research project between faculty at
NCSU and Bowman-Gray Medical School demonstrated that enriched protease inhibitor
fractions could be obtained from senesced tobacco (Figure 13.2). The initial process tech-
nology used was as described above. The crude F-2-p fraction was precipitated using
ammonium sulfate and heating at 80°C for 10 min at pH 4.5. This was followed by Sepha-
dex G-75 size exclusion chromatography and, ultimately, agarose-chymotrypsin affinity
chromatography to obtain pure tobacco Chymotrypsin Inhibitor-1 (CH-1) (St. Clair and
Danehower, unpublished data). Bioassays of CH-1 indicated significant activity in the sup-
pression of radiation-induced transformation of a C3H/10T1/2 cell line. Results were com-
parable to those for the soybean-derived “Bowman Burke Inhibitor” that has been widely
studied for its anticarcinogenic potential.
© 1999 by CRC Press LLC

FIGURE 13.1
Process flow and tobacco bioproducts resulting from the bioprocessing of Nicotiana tabacum. (Process flowchart:
solid lines = process development to date, dashed lines = future process development. Bioproducts: underlined =
intermediate fractions, bold = final products.)
© 1999 by CRC Press LLC
13.3 Tobacco Bioprocessing — The Present
The F-2-protein mixture also has been shown to contain foreign proteins expressed by
transgenic tobaccos.
60
Because of tobacco’s ability to be transformed reliably using a num-
ber of molecular biology techniques, numerous foreign proteins and, to a lesser extent,
FIGURE 13.2
Isolation of protease inhibitor-I from bioprocessed tobacco. (From St. Clair, W. and Danehower, D.A. Unpublished
data.)
© 1999 by CRC Press LLC
their resultant products have been expressed in this crop and many have been subse-
quently isolated in significant quantity (see Owen and Pen
46
and Goddijn and Pen
19
for cur-
rent reviews of plant-based biochemical production). Numerous papers have appeared in
the literature arguing that field-grown plants provide a low-cost alternative to prokaryotic
microorganism-based production of transgenic products. One argument put forth is that
eukaryotic plants have a greater capacity for post translational processing of complex pro-
teins.
19
Secondly, the use of field-grown plants as “bioreactors” is a relatively cheap and
almost infinitely variable system for foreign protein production. While is it true that pro-
duction costs are less expensive in field-grown plants than in fermentation systems, it is

equally true that subsequent isolation of foreign proteins from green plant biomass may
present considerably more difficulty than extraction from bacterial cell biomass. Successful
demonstration of the ability to isolate foreign proteins from green plants is critical to the
ultimate success of plant bioprocessing.
At NCSU, recent research has demonstrated proof of concept for the production of a for-
eign gene product with commercial potential and the subsequent ability to isolate that
product in high purity (Figure 13.3).
60
In this project, tobacco was transformed with a gene
for expression of bovine lysozyme, a 15 KDa antibacterial protein with a broad array of
uses including medicinal, agricultural, and industrial applications against animal and
plant pathogenic bacteria.
39
The gene was coupled to a CaMV 35S promoter and a select-
able marker. This construct was transferred into an Agrobacterium system that was then
used to transform the tobacco. Following recovery of transformed plantlets, a heteroge-
nous array of transformed plants were grown in a greenhouse. Expression levels were cal-
culated using SDS-PAGE densitometry for several groups of transformants. The highest
level of expression was 1.8% of total F-2-p protein or approximately 1% of total plant pro-
tein. Yields of lysozyme could ultimately be higher as this system was not optimized for
expression of the lysozyme gene.
FIGURE 13.3
Downstream bioprocessing of bovine stomach lysozyme from tobacco.
© 1999 by CRC Press LLC
Plants were harvested and immediately processed for protein using a procedure similar
to that described earlier. The aqueous F-2-protein stream was processed through an ultra-
filtration system equipped with a 30 KDa exclusion limit membrane filter. Subsequently, a
second ultrafiltration system consisting of a 1-kDa exclusion limit membrane was used to
further purify the lysozyme fraction while concurrently dialyzing the sample and reducing
the volume 10-fold. The final step of the purification process was ion exchange chromatog-

raphy using Hyper D-S resin. The sample was introduced using a 0.01 M acetate solution
at pH 6.0. Following washing to remove other proteins, the purified lysozyme fraction was
eluted with 0.1 M acetate at pH 8.0.
Separation mechanisms used in this process were chosen based upon their ability to be
scaled up. This is clearly a successful demonstration of proof of concept for the production
and downstream isolation of a foreign protein from the tobacco f-2-protein mixture. While
the level of purity obtained in these experiments is not sufficient for medical uses of bovine
lysozyme, the purity obtained is more than sufficient for its use as an industrial and/or
agricultural antibacterial agent.
13.4 Other Product Streams from Bioprocessed Tobacco
In order to increase the commercial attractiveness of tobacco bioprocessing, it is critical that
as many profitable product streams as possible be obtained. Thus far the production of
native and foreign proteins in field-grown tobacco has been considered. Another class of
biochemicals, i.e., low molecular weight tobacco bioproducts, also have been the subject of
research. Economically significant biochemicals produced by tobacco include chlorophyll
and carotenoids, starch, diterpenes, saccharide esters, alkaloids, polyphenols, long chain
hydrocarbons and waxes, coenzyme-Q, and structural carbohydrates (biomass). Some of
these products already have significant commercial potential and could fit well into an
overall tobacco bioprocess. The most promising of these are discussed below.
13.4.1 Carotenoids
Most carotenoids are currently derived from synthetic chemical processes. Nevertheless, a
resurgent market demand for natural vitamins and pigments has created a potential mar-
ket for plant-derived carotenoids. Natural carotenoid pigments are used extensively in the
poultry and fish industries.
28
These compounds have long been items of commerce as
vitamins
59
and are increasingly recognized as an important factor in resistance to disease.
18

A recent trend in carotene-based vitamins has been the use of naturally occurring vitamin
mixtures, rather than single pure components. This trend could result in less need for high-
cost downstream processing of carotenoid isolates.
The tobacco carotenoids consist primarily of beta-carotene with lesser amounts of xan-
thophyll, violaxanthin, and neoxanthin.
58
The pigment/starch “sludge” obtained during
the initial centrifugation step in F-1-protein processing would be an excellent material for
recovery of carotenoids. Successful isolation would require that the bioprocess minimize
oxidative conditions by excluding light and oxygen. Solvent extraction of the pigment/starch
mixture, followed by basic hydrolysis to remove chlorophyll would be one approach which
might be taken to recover carotenoids. Tobacco starch, consisting of a mixture of amylose
and amylopectin in a 1:4 ratio would be a by-product of this process.
© 1999 by CRC Press LLC
13.4.2 Terpenoids
Tobacco-derived terpenoid secondary products have long been important to both the
tobacco and flavor and fragrance industries. Tobacco essence, which is in part derived from
the oxidative breakdown of the diterpenoid duvatrienediols found in glanded trichomes
on the leaves of N. tabacum are highly valued as an ingredient in fine perfumes.
42
Similarly,
certain N. tabacum biotypes produce the bicyclic diterpene, cis-abienol, while N. glutinosa
produces sclareol, a related bicyclic diterpene. Both cis-abienol and sclareol can serve as
precursors to sclareolide, a valuable “fixative” in the fragrance industry.
These diterpenes also have other notable properties. The Japanese have patented the use
of Nicotiana diterpenes as both antifungal
24
and antineoplastic agents.
40
Research at NCSU

and elsewhere
11-15,31,38
has resulted in further identification of these leaf surface diterpenes
as antimicrobials and/or plant growth regulators.
13.4.3 Sugar Esters
The so-called “sugar esters” of Nicotiana (typically a mixture of sucrose and fructose esters
to which a mixture of short-chain linear and methyl-branched fatty acids are esterified) are
the subject of serious study by scientists at the USDA. These researchers have found the
sugar esters to be excellent natural insecticides.
2,3,48
As in the case of the diterpenes, these
compounds also have been shown to have significant antimicrobial and plant growth reg-
ulatory activity.
9,12,13
A recent paper
23
determined that up to 11 lb/acre could be produced
from N. gossei at traditional tobacco production planting densities (18 K plants/ha). Yields
should be even higher in close-grown plots.
13.4.4 Hydrocarbons and Waxes
High molecular weight waxes and hydrocarbons, such as those found on the leaf surface
of tobacco, have been touted
8
as an alternative to fossil-fuel petroleum lubricants. Although
the quantities of these compounds are relatively small in tobacco, they would be worth
examination as a by-product stream in the production of diterpenoids and/or sugar esters.
Removal of hydrocarbons and waxes using either solvent partitioning or chromatographic
techniques is a key step in the purification of leaf surface diterpenes and sugar esters. Thus,
these compounds might be obtained in relatively high purity with little subsequent pro-
cessing beyond solvent removal.

13.4.5 Coenzyme-Q
Coenzyme-Q is a widely utilized drug for the treatment of heart disease in Japan and West-
ern Europe.
33
This natural vitamin/cofactor has superior antioxidative properties in blood,
thereby decreasing the formation of low density lipoprotein.
53
The Japanese currently pro-
duce coenzyme-Q in a tobacco cell fermentation system. The potential for selection of lines
which produce high levels of Coenzyme-Q in the field should be examined.
13.4.6 Structural Carbohydrate
Finally, the residual cellulosic fraction (biomass) that arises from the overall processing of
tobacco for alternative uses may have value for the production of alcohol fuels, paper, and
© 1999 by CRC Press LLC
other chemicals.
6,41
Scientists in the pulp and paper department at NCSU have produced
paper-like products from the cellulosic biomass which is the final byproduct of the process-
ing of tobacco for protein (R. C. Long, personal communication). Perhaps a more attractive
use of residual biomass is in the production of alcohol or biogas fuels. The stalks from tra-
ditional tobacco production systems have been examined as a feedstock for the production
of methane in a synfuels demonstration facility.
13.5 Tobacco Bioprocessing — The Future
Despite a long record of research on the uses of bioprocessed tobacco as a renewable
resource for proteins and low molecular weight fine chemicals, much work remains before
tobacco bioprocessing becomes a commercially viable enterprise. Critical issues must be
addressed including a reduction in the costs of field production and enhancement of bio-
mass yield. Key areas for research here will be alternatives to the economically and envi-
ronmentally costly use of fumigants for bed preparation and control strategies for bacterial
rot in secondary harvests.

In addition, effort must be directed to optimization of the tobacco plant for use in biopro-
cessing. Plant lines need to be developed which are better suited biochemically for biopro-
cessing. Examples include the need to develop plants with decreased polyphenol and
alkaloid content. Polyphenols bind to and interfere with recovery of proteins while the
presence of alkaloids raises issues of consumer and regulatory acceptance. Tobacco lines
that produce enhanced levels of high-value natural products also are desirable. An exam-
ple here might be the development of tobacco varieties that produce high levels of commer-
cially valuable (and marketable) sclareol in place of the duvatrienediols.
Improvement in the initial F-1-p and F-2-p recovery process is another important goal.
Improvements in protein recovery require a careful examination of homogenization condi-
tions, the addition of protein solubilizing agents, reductants, agents for the removal of
polyphenols, flocculation techniques, the use of cellulases for cell wall degradation (pro-
duced in planta?), and clarification procedures. Perhaps the greatest opportunity for
decreasing costs is the development of relatively low-cost downstream processes for high
value proteins and natural products. Production and yields of these products are the ones
most likely to “make or break” tobacco bioprocessing. As has been demonstrated,
60
it is
possible to obtain good yields of engineered proteins in relatively high purity using cost-
effective technologies such as selective precipitation, dynamic membrane filtration and
diafiltration, and ion exchange chromatography.
The bioprocessing of more exotic proteins for use in medicine is more problematic. On
the one hand these products have tremendous value and could greatly increase the per acre
profit. Conversely such products require a high standard of process sanitation and must be
isolated in a purity which will require the use of more expensive downstream bioprocess-
ing techniques such as aqueous two-phase partitioning and the use of highly selective
membrane filtration. Despite these problems, the potential payoff for such products is so
great as to warrant further study in this area. Processes that might be examined include
expanded bed adsorption, size exclusion, and affinity chromatography.
The potential to enhance the product stream of bioprocessed tobacco by isolation of valu-

able low molecular weight products has received much less attention. A clear-cut demon-
stration of proof of concept is needed for these materials. Logical products to pursue
include carotenoids, leaf surface diterpenes, and sugar esters. An obvious process stream
© 1999 by CRC Press LLC
for carotenoid recovery, the green “sludge” fraction already exists. Techniques such as base
hydrolysis of chlorophyll and subsequent solvent partitioning are well defined carotenoid
recovery methods. The increased marketability of mixed carotenoids enhances the attrac-
tiveness of this product stream. In the case of the diterpenes and sugar esters, methods
must be developed which will permit isolation of a crude mixture prior to protein isolation
without effecting subsequent protein recovery. In the case of sclareol, a clear market exists.
The sugar esters could be niche marketed as natural insecticides.
While tobacco bioprocessing research is important, it is equally important to identify and
cultivate potential markets for the products. The likelihood of success improves tremen-
dously when the marketplace, rather than the technology, drives development. At present,
tobacco bioprocessing is largely technology driven. In order to ensure the highest potential
for success of this technology, a critical, but unmet, need is market analysis and the devel-
opment of wider contacts with manufacturers. Significant efforts have been made in this
area,
55
but further work is required before the entire array of products that will be required
for a successful economic tobacco bioprocessing “package” can be obtained. Several scien-
tists have discussed the development of industrial crops.
7,16,22,32,35
Invariably, these authors
stress the importance of prior analysis of markets and prices before beginning work on any
industrial crop development. They also emphasize the need for close coupling of research
with market development and penetration strategies.
There are a number of advantages to plant-based production of biochemicals. Plants
have significant advantages over most synthetic chemical production systems as they are
capable of producing enantiomerically pure compounds. As eukaryotes, plants can pro-

duce more complex foreign proteins, a significant advantage over the prokaryotic bacteria
used in industrial bioreactors.
While this chapter has focused upon the potential benefits to farmers of this technology,
it is important to note that plant bioprocessing requires close coupling of agricultural and
rural industrial development. Thus, crop bioprocessing would provide excellent returns to
farmers while offering good industrial jobs to rural residents. If planned properly, plant
bioprocessing also promises to be a relatively benign industry in terms of the environment.
The use of renewable resources would lessen our dependence on a petrochemical-based
economy, resulting in greater security for those countries who have invested in plant-based
industries.
Of course, there also are disadvantages that must be addressed and significant techno-
logical hurdles to overcome. These include the risks involved in such a radical departure
from current methods for producing biochemicals. Even a technology that has the many
advantages outlined above is not guaranteed success in the marketplace. As development
of plant-based technologies proceeds, it is imperative that a close coupling of production
scale-up and marketing be maintained.
In summary, it is our belief that the potential for plant-based production of biochemicals
as items of commerce is strong. Field-grown plants can indeed function as “bioreactors”.
What is required is a focused research effort that includes early and careful consideration
of the market potential for the proposed products. The research program must develop a
complete research team which is sufficiently funded and capable of undertaking a coordi-
nated project including basic and applied research in agronomics, plant molecular biology,
chemistry and biochemistry, and process engineering. New product development must be
done with careful consideration of markets and marketing. As new products are developed
they must be incorporated efficiently initially into pilot-scale processes and ultimately into
full-scale industrial processes. Concurrently, corporate support and market development
expertise must be available to ensure the success of the product(s). Unfortunately, the
short-term mindset of both industry and, yes, even academia, make such an undertaking
© 1999 by CRC Press LLC
all the more difficult. Nevertheless, it is our strongly held belief that such an undertaking

is possible, and, more importantly, has great potential to create a new paradigm for indus-
trial biochemical production with concomitant benefits to farmers, industry, consumers,
and the environment.
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